This invention relates to digital data communications over distance-limited wire media. In particular, this invention relates to an apparatus for extending the propagation distance of digital data signals.
There is a need to provide means to extend the effective distance over which digital data signals are communicated via wire in an outdoor environment. Distances may be greater than be supported by the conventional routers and switches. For example, known implementations of 100 BASE-TX physical layer integrated circuits such as the Broadcom AC104QF (from Broadcom, Inc.) typically handle only up to 150 m (492 ft.) of Category 5 cabling at room temperature for speeds up to 100 MBPS. Moreover, power consumption becomes a serious concern because power must be supplied and distributed by the outdoor network. Alternative schemes such as optical fiber are not cost effective for all applications, particularly over relatively short distances of several hundred meters.
A standard has been adopted for electrical and magnetic isolation of electronic circuitry intended to be operated in a severe outdoor environment. The standard is referenced as IEEE 802.3u, IEEE 802.3ab and ANSI X3.236. The specifications provide for operation in a temperature range between 0 and 70 Celsius. For extended operation between −40 C and +85 C, which is more typical of actual experience in some environments, adoption of this standard would be inadequate for reliable operation. Because Category 5 cabling and installation are less expensive than the fiber optic alternative, it is desirable to be able to go farther than the 100 m (328) feet required by the IEEE standard using a low cost cable extender that is powered from the upstream network cable.